1. Field of the Invention
The present invention relates to a lens-driving unit utilizing a flexible printed wiring board.
2. Description of Related Art
Conventionally, many imaging devices such as digital cameras adopt a type whereby a lens group moves in an optical axis direction. Based on such a type, the lens group is generally held by a lens group holding frame. The lens group holding frame is disposed so as to slide along the optical axis through a guide member provided for a casing.
Furthermore, such an imaging device is mounted with a lens-driving unit for driving the lens group holding frame. As the lens-driving unit, for example, lens-driving unit described in Japanese Patent Publication Nos. 2006-098577 and 2005-057837 are proposed. Such lens-driving units are provided with drive means and a flexible printed wiring board.
The drive means is drive the lens group holding frame using a drive force outputted from a driving device. On the other hand, the flexible printed wiring board is supply a control signal and drive power to the driving device. This flexible printed wiring board is made to bend in the optical axis direction so as to connect with the drive source to the power supply and control section. This allows, even if the lens group holding frame moves to slide in the optical axis direction, the flexible printed wiring board to follow the movement thereof.
However, in the lens-driving unit described in Japanese Patent Publication No. 2006-098577, a piezo-element as a drive source extends perpendicular to the optical axis. Therefore, in this lens-driving unit, the direction of the driving device is different from the bending direction of the flexible printed wiring board. Therefore, the size of the lens-driving unit must be set to be long in the optical axis direction and the direction perpendicular to the optical axis direction respectively. This may cause the size of the lens-driving unit to increase.
On the other hand, in the lens drive device described in Japanese Patent Publication No. 2005-057837, an oscillating wave linear motor as a drive source extends in the optical axis direction. For this reason, in this lens drive device, the direction of the drive device is the same as the bending direction of the flexible printed wiring board. Thus, this lens drive device can reduce the length in the direction orthogonal to the optical axis direction. Therefore, this lens-driving unit is able to make the lens-driving unit more compact.